Commitments and Contingencies - Restricted Cash and Marketable Securities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Restricted Cash and Marketable Securities [Abstract]
Capping, closure and post-closure obligations	$ 31.0	$ 30.6
Insurance	86.7	99.4
Payment for maturing tax-exempt financing	0.0	49.4
Total restricted cash and marketable securities	$ 117.7	$ 179.4	$ 115.1	$ 108.1

The noncurrent cash, cash equivalents and investments that is restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits classified as long-term; that is not expected to be released from such existing restrictions within one year of the balance sheet date or operating cycle, whichever is longer. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Includes noncurrent cash equivalents and investments that are similarly restricted as to withdrawal, usage or disposal.

No definition available.

Name:	us-gaap_RestrictedCashAndInvestmentsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant